The identification of animals is important in animal husbandry for a number of significant reasons, for example, in modern milking systems where the milk output and sometimes the quality of milk for each individual cow is monitored. In order to associate the production data with the correct cow, there must be provided a technique for entering the identification of the cow to the recording apparatus receiving the data. This may be done conventionally by an operator punching in the identification number appearing on the cow. However, such a procedure is waseful of the operator's time and subject to errors.
Optical sensing apparatus could also conceivably be used for sensing the presence of a cow in a milking system. Such apparatus would have the disadvantage that it is sensitive to the presence of dirt and dust which can interfere with proper operation thereof.
Other applications for animal sensing apparatus may be in monitoring feeding by animals. Electronic apparatus has been developed for monitoring the entry of an animal's head into a feeding enclosure and employs a transponder employing a resonance circuit. Additional possible applications may be found outside the area of animal husbandry, such as the monitoring of prisoners in a penitentiary.